<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        p {
            font-size: 25px;
            font-weight: 800;
        }

        div {
            margin-left: 100px;
            float: left;
        }
    </style>
</head>
<body>
<p>点击复制可以复制textarea中的内容，任何textarea下点击粘贴按钮，可以将复制的内容粘贴到该textarea中</p>
<hr>
<div>内容:<br>
    <textarea name="" cols="30" rows="10" id="a0"></textarea><br>
    <input type="button" value="复制" id="a1"onclick="f(this.id)">
    <input type="button" value="粘贴" id="a2"onclick="f1(this.id)">
</div>
<div>内容:<br>
    <textarea name="" cols="30" rows="10" id="b0"></textarea><br>
    <input type="button" value="复制" id="b1"onclick="f(this.id)">
    <input type="button" value="粘贴" id="b2"onclick="f1(this.id)">
</div>
<div>内容:<br>
    <textarea name="" cols="30" rows="10" id="c0"></textarea><br>
    <input type="button" value="复制" id="c1"onclick="f(this.id)">
    <input type="button" value="粘贴" id="c2"onclick="f1(this.id)">
</div>
<div>内容:<br>
    <textarea name="" cols="30" rows="10" id="d0"></textarea><br>
    <input type="button" value="复制" id="d1"onclick="f(this.id)">
    <input type="button" value="粘贴" id="d2"onclick="f1(this.id)">
</div>

<script>
    var fz ="";
    function f(val) {
        var a = val.split("")[0]+"0";
        fz = document.getElementById(a).value;
    }
    function f1(val) {
        var a = val.split("")[0]+"0";
        document.getElementById(a).value = fz;
    }
</script>
</body>
</html>